Large animal farming operations, for example dairy cow operations, may involve housing a large number of animals in a barn. Such operations require constant cleaning of the considerable quantities of manure produced by the animals. In a barn of this nature, solid or semi-solid manure together with solid bedding material (e.g. sand) is typically collected and dumped into an intermediate holding tank in the barn where water is added to the solids to produce liquid manure in the tank. The liquid manure and solid bedding material may be spread in a lane in the holding tank for recycling of the bedding material from the material. The liquid manure and residual bedding material may then be transferred to large reservoirs (lagoons) located outside the barn where the liquid manure is stored until transferred to liquid manure spreaders for application as fertilizer to farm fields.
Liquid manure typically comprises particles of solid manure suspended in water. Transferring the liquid manure from the intermediate holding tank to the large reservoir requires both agitating, to ensure that the solid manure and residual bedding material is adequately suspended in the water, and pumping to move the liquid manure through conduits to the large reservoir. Such transfers are typically accomplished with the use of at least two pumps, one for agitating the liquid manure and one for pumping the liquid manure. The agitating pump typically comprises a recirculating pump that simply cycles liquid through a recirculation path. Further, because the pumping operation is accomplished in a relatively short period of time, the agitating operation needs to be performed for a sufficiently long period of time prior to pumping to ensure adequate suspension of manure particles in the water. Typically, an operator will first turn on the agitating pump and then after a predetermined period of time turn on the transfer pump.
There are a number of problems with the typical method. Two pumps are required, one for agitation and one for transfer, resulting in added equipment cost and maintenance requirements. A significant amount of operator time is required to turn on the pumps at appropriate times, resulting in less operator time available for other activities required in a busy large animal farming operation. And, inadequate agitation from the recirculating pump either prevents complete emptying of the intermediate holding tank or necessitates longer agitation time to ensure complete emptying.